On the scattering of test data and the significance of the standard coefficients ‘dynamic stiffness’ and ‘loss angle’ for hydraulic engine mounts

Based on the test results, a study on the scattering of the standard coefficients c _dyn and δ within the test cycles on a standard testing machine as well as within the samples of a batch of hydraulic engine mounts is performed; furthermore, an estimate for the systematic error caused by the testing machine is given. By a simulated example, the pronounced sensitivity of the response of the engine to the scattering of c _dyn and δ as well as to even small deviations of the hysteresis curves for otherwise identical values of the standard coefficients is demonstrated. As a main result, it is found that the most important source of uncertainty is scattering within the batch, which, in conjunction with the observed sensitivity of the response of the engine, raises the question for the meaningful level of sophistication of a model for predictive purposes.     

Estimation of wheel–rail friction for vehicle certification

In certification of new rail vehicles with respect to running characteristics, a wide variety of operating conditions needs to be considered. However, in associated test runs the wheel–rail friction condition is difficult to handle because the friction coefficient needs to be fairly high and the friction is also generally hard to assess. This is an issue that has been studied in the European project DynoTRAIN and part of the results is presented in this paper. More specifically, an algorithm for estimating the wheel–rail friction coefficient at vehicle certification tests is proposed. Owing to lack of some measurement results, the algorithm here is evaluated in a simulation environment which is also an important step towards practical implementation. A quality measure of the friction estimate is suggested in terms of estimated wheel–rail spin and total creep. It is concluded that, tentatively, the total creep should exceed 0.006 and the spin should be less than 1.0 m^?1 for the algorithm to give a good friction estimate. Sensitivity analysis is carried out to imitate measurement errors, but should be expanded in further work.     

斜井盾构推进系统的栽头调整能力研究

为降低斜井掘进过程中盾构推进系统在栽头调整上存在的主观性与不确定性,从地基沉降量的角度入手,提出栽头的沉降量描述,并基于温克尔弹性地基模型,建立斜井盾构栽头的沉降量描述模型。然后结合载荷对于栽头调整的影响,进一步建立用于描述斜井盾构推进系统栽头调整能力的数学模型,并给出其上下限值的计算条件。基于栽头调整能力的数学模型,以内蒙古新街台格庙煤矿斜井工程为背景,研究隧道设计坡角变化对栽头调整能力的影响。结果表明： 1）随着下坡角度不断增大,推进系统的栽头调整能力的上下限不断下降; 2）随着下坡角度不断增大,盾构下滑力的迅速增长是造成推进系统栽头调整能力不断下降的主要原因。     

相继增压对某型柴油机性能影响及喷油参数再优化

对某采用相继增压与可控进气涡流复合系统的柴油机建立了缸内仿真模型,分别对可控进气涡流系统和相继增压与可控进气涡流复合系统的燃烧过程进行仿真计算,结果表明,在低工况下后者排气中NOX、Soot的质量分数分别降低了54%和86.1%。并对相继增压与可控进气涡流复合系统柴油机喷油提前角、喷雾锥角进行了再优化仿真计算,结果表明,优化后喷油提前角为20°CA,喷雾锥角为155°。     

某码头靠船构件改造与加固

为解决珠海某拖轮码头因靠船构件尺寸偏差无法靠泊船舶的问题,设计了在原混凝土靠船构件表面粘贴角钢的方案,既可将原靠船构件向下延伸1 m,又对其悬臂端部进行加固补强。靠泊力复核和有限元验算表明:改造后靠船构件满足船舶停靠要求,改造施工和工程回访亦表明3 a来码头运营正常、钢结构主体完整。该靠船构件改造和加固案例可为类似工程提供借鉴与参考。     

H+OBr→HO+Br产物的散射和角动量取向

用准经典轨线的方法对H+OBr→HO+Br反应产物的散射和产物角动量进行了研究.计算中的碰撞能为0.5、1.0、1.5、2.0 e V并且初始振转动能级为ν=0,j=0.结果显示,在四个碰撞能下的散射和产物角动量取向有不同的特点.同时从反应机理和势能面的角度分析了它们对碰撞能的影响.     

摩托车发动机点火提前角对发动机性能影响的实验研究

摩托车点火提前角对摩托车性能有较大影响,其中对摩托车NO。排放量的影响最大。随着点火提前角的增大,NO。排放量也相应增加,为控制NO。的排放量,点火提前角必须尽可能小;另一方面,随着点火提前角的变小,发动机功率也变小,发动机动力性变差,进行电喷标定或摩托车点火器设计时,必须两者兼顾,从而找出一个最佳的点火提前角。     

基于EMD理论的等角度重采样方法在凸轮轴故障诊断中的应用

将一种无转速测量信号,基于希尔伯特—黄变换等角度重采样的阶次分析方法应用于发动机凸轮轴故障诊断,从而有效消除转速波动的影响,使信号处理与分析结果更加准确.应用所提出的方法对某6缸柴油机缸体振动信号进行分析,对比凸轮轴轴瓦断裂修复前后振动信号特征的变化,有效地提取出了故障特征.     

汽车侧偏角与横摆角的仿真与估计

为了提高汽车操纵稳定性和安全性,设计汽车状态观测器模型对难以测量的质心侧偏角与横摆角速度的数据进行估计是很有必要的。本文利用扩展卡尔曼滤波算法并基于二自由度汽车模型上对质心侧偏角进行估计及仿真分析,仿真的结果与估计的结果吻合,估计结果具有较高的应用价值。     

三氧化钨薄膜的制备及其亲水/疏水性能转变研究

在预先用聚多巴胺薄膜处理的玻璃基底上,采用溶胶-凝胶法制备出三氧化钨(WO3)薄膜,用X射线衍射(XRD)和扫描电子显微镜(SEM)表征手段来分析其物相组成和形貌特征.对WO3薄膜在UV光照射下和黑暗的环境中发生亲水/疏水转换的现象进行研究,最后得出WO3薄膜表面润湿性转化的机理.